I remember doing this question!
*dives into the past papers*
I also remember doing it wrong and teacher correcting me
I can do the first part though...
Using the chain rule, we know:
and if you substitute that in, you'll get this:
I'm not really sure because I can't get to your equation...
And sorry for the "d", it takes too long time to straighten them...
You're looking for
Now, (we have to do it because the variable is t in the brackets, not x).
Using the product rule :
Edit : oh I see, you made a typo, Air
Re-edit : too fast for me Mr F